We propose to use SAXS to measure DNA bending in complexes between DNA oligomers and the switch activation protein SAP1 from the yeast S. pombe. Preliminary data taken at SSRL provide strong evidence for an architecture of the SAP1 dimer involving a leucine zipper coiled coil attached to the DNA binding region. Measurements of the effects of mutations of SAP1 on resulting DNA bending will help in the construction of a structural model of the switch-activating function of SAP1.